Reinforced concrete structure in an electrolytic furnace house for producing aluminum



Feb. 23, 1965 R. HEGLAND 3,170,362

REINFORCED CONCRETE STRUCTURE IN AN ELECTROLYTI FURNACE HOUSE FORPRODUCING ALUMINUM Filed Oct. 10, 1961 f 5. 0 m b 7 3 2 m Z Z P 3 .....pB 9 2 7 Z a a 7 4 10. 1 7 m 4 Z T, 5 7 7 A 5 7 z z a M Z a a o 7 M 3 2 5I: f 1i 6 3,170,862 1 REINFORCED CONCRETE STRUCTURE IN AN ELECTROLYTICFURNACE-HOUSE FOR PRO- DUCING ALUMINUM f r Reidar 'Heglan'd, Zurich,Switzerland, assignor to Swiss Aluminium LtdL, Chippis, Switzerland, ajoint-stock company of Switzerland Filed. Oct. 10,1961, ser. No. 144,095

Claims priority, application Switzerland, Oct. 14, 1960,

9 Claims.. '(Cl. 204-244) .The present invention relates to a reinforcedconcrete structure in an electrolytic furnace house for producingaluminum. a I

Electrolytic furnaces used in the production of aluminum froma fluoridemelt by the usual processes include essentially rectangular potsarranged in straight rows in a. furnace house and anode structuresincluding anodes .dip-

ping into the pots. The pots may be situated at fioor levelv and areadvantageously directly supported on foundations or: bracketsa'rrangedunder the floor. These foundations or brackets, and indeed the whole ofthe lower part of the building, normally" consists of reinforcedconcrete. The anode structures of the furnaces are'carried'by steelsupports or by pillars of reinforced concrete, which may extend up fromthe floor or which may have their-foundations below the floor. V Inmodern electrolytic installations, a large number 0 furnaces, allrequiring a current of 80,000 amperes and even more, are connected inseries. In such installations, potential differences of several hundredvolts wtih respect to earth exist; on the rectifying side, the potentialdifference may be up to 1,000 volts and even more. It ispractically'impossible to electrically insulate completely all thefurnaces, bus bars and Waste gas conduits from the building structure.Hence, stray currents will alwaysfiow into the reinforced concretestructure. Concrete, being an electric conductor when damp, and being asemi-conductor when dry, c annot under any circumstances be regardedas-an insulator. Stray cur-rents flowing through the concrete may reachthe reinforcement and flow through said reinforcement, heating therebythe reinforcement. The resulting thermal expansion of the reinforcementcauses cracks in-the concrete, and the electrolytic action of thecurrent anodically oxidizes the ferrous reinforcement,

causinggit to rust. Also, stray currents create current losses and are asource of, danger to the operators.

One object of the present invention is to provide anew and improvedreinforced concrete structure which supports the electrolytic furnacesina furnace orpot'house V for the pro ductionaof aluminum, and whichavoidsthe drawbacks of theprior art described above.

; According to thepresent invention, the:reinforced and eventually fromthe walls of the building.

The complete structure normally includes a sub-floor,

concretewtructure for; supportingthe" furnace is divided into. separatesections, which are electrically insulated in yer ti; calland-horizontal. direction fro'rn one another, from earth I one another.What is important is to divide the structure; a

such sections, This sectionalized structure advantageously rests onfoundation pedestals extending into the ground; and is separatedfronrthe'se pedestals-by electrically in- "sulating layers. j j t The.sections may constitute is ds of reinforced'com' 'crete which arelvertically insulatedfzfrom one auother by the spacebetw een thernfthefurnace pots beingarr'ang'e'd between the islands. -The floor may ib eyformed by cohjcret slabsl'garried by but electrically insulated fromtheir that consists of the floor a nd the vertical supports intoislands, and by bridging islands and electrically insulated from them.An island may support more than one floor slab and these slabs are;preferably electrically insulated from one another Such.

slabs extending between the slabs onislands may be cast in situ or bepre-cast. The electrical insulation may be formed by layers of a aplastic, which may be an-epoxy-or polyester resin applied by pouring orspraying and which is preferably reinforced by glass fibres. 'Forinstance, the slabs of the floor may,

be made, and insulated from the concreteisland that supports them, byfirst pouring a layer of polyester resin V I onto the island. A glassfibre mat is placed on this layer and pressed in, and another layer ofpolyester resin may be applied. After the layer of the resinhashardened,

the floor slabs are cast in concrete and the separating joints betweenthem are filledby pouring in polyester v-resin. E lectrical'measurementsmadebetween a copper plate placed on a floor slab and electrodesconcreted into an island below it have shown that, with 220volts A.C'.

across the electrodes the resistance between them is multipliedmore'than one hundred times bythe intermediate .layer of plastic,provided the concrete is:fully set;

The preferred construction according to the invention will now bedescribed in detailwith reference to the accompanying drawings, inwhich: 7

FIGURE 1 is a horizontal somewhat diagrammatic sec Y tion of a part of afurnace house embodying the present invention, taken on lines .11 ofFIG. 2;

FIGURE 2 is a somewhat diagrammatic section through the whole width ofthe furnace house, taken on the lines 22 of FIGURE 1; and

7 FIGURE? shows in section a modification of a portion of thestructureof the furnace house in accordance with the present invention.

Referring to FIGS. 1 and 2 of the drawings,tthe furnace house shown hasside walls 15 spanned by a floor 17 *which lies above abasernent chamber13. Furnace pots Z-Containing fiuoridetmelts into which anodes 19 dipare disposed at the level of 11611001 17- inholesleft in the floor, andeach pot is carried on aflgrate 9 which, pro jects= laterally to rest onI-girders 10, TheI-girders 10 are carried by the. reinforced concretestructure which as a whole'rests on'a sub-structure comprisingfoundation pedestals. 11 extending into the ground. Thefreinforcedconcrete structure comprises side-supports land centralf supports (1abuilt as separate islands with cantilever extensions 21 and withbrackets8 forthe support of the girders It j' lhese brackets 8 are-constructedso that the[ pots ,2 can be-lowered between the brackets'an'd removedfor repair Or eplacemenL,

The reinforced concrete structure that 'supporfts' thefun naces isinsulated from the substructurethatconsists 2 consi'sting VI of apolyester resin reinforcedby glass'fibr'e. v Thecon- '1 i essentially"the pedestals 11 by"tfoughs nections between thereinforcedc'bncrete structure and the pedestals 11 may be formed bysuspending each trough 12 in the shuttering in which the correspondingpedestal is formed, and pouring'the concrete herieath the troughtoformthe corresponding pedestal.

The pots 2 arearran ged in two, rows; and in each row'," f the openingsthat'receive the pots a're all connected with} one another, so thatthere is a continuous division of the i floor into three longitudinalparts 3a, 3b, 3c,electricallyseparated from one another. 4

' v The brackets 8 have 1load-bearing'coverings 7 on which the girders10 rest andeach covering 7 is electrically inthe remainder of the*bracket by insulation 127. i l V i 1 The extensions 21 of the sidesupports Iproject inv wardlyfrom'each'side of the houserandhave' narrowends extending. intotl'ie spaces between adjacent furnace pots sulatedfrom Patented Feb. 23, 1965 U 2. In addition, the extensions 21 of thecentral vertical supports 101 have similar narrow ends projectingoutwardly from the center line of the house into the same spaces.

The floor 17 is composed in part of concrete slabs on the tops of theislands 1 and 1a separated by insulations 20 and in part of slabs 4bridging the islands. The slabs 5 are formed on top of insulating layers6 in the manner described above, and in the parts of the floor betweenthe rows of furnace pots 2, these slabs 5 do not wholly cover the topsof the islands but extend short of the sides of these islands to defineledges on these islands to receive the ends of the slabs 4, which areprefabricated. Insulation 22 is interposed betweenthe slabs 4 and theseledges.

Pillars 13 provided to support the anodic parts of the furnaces rest onthe cantilever extensions with the interposition of insulation 14. Thesepillars 13 carry the anodes 19 in the usual way, the anodes being fedwith current through bus bars 23 and conductors 24.

The furnace house, of course, includes a superstructure including wallsand a roof not shown and this is insulated from the structure thatcarries the furnace pots 2 by the insulating layer 6. Alternatively, thewalls 15 may be of a metal framework 16 with a covering, as shown inFIGURE 3, and in such a case a trough 25, similar to the trough 12 maybe let into the top of the structure immediately below the wall, andsteel pins and plates 26 may then be concreted into the trough to formsupports for the framework 16.

If it is necessary for reinforcement to extend through any joint, e.g.through the joint between the pillars 13 and extensions 21 beneath them,the reinforcing rods will tend to conduct current and destroy the effectof the insulation, such as that shown at 14. To remedy this, thereinforcing rods may be coated with a firmly adherent coating of anelectrical insulating plastic, to which grains of sand may be bonded,all as described and claimed in copending application Serial No. 120,624filed June 29, 1961, now abandoned.

The different insulations referred to may comprise a resin, such as anepoxy resin, or a polyester resin reinforced with glass fibres, asdescribed.

What isclaimed is:

1. A furnace house for furnace pots used in the electrolytic productionof aluminum, comprising side walls, and means for supporting a pluralityof furnace pots between said walls comprising a foundation structure, afloor supporting reinforced concrete structure supported on saidfoundation structure and constituting a plurality of sections extendingbetween said walls and said furnace pots, means for supporting thefurnace pots on saidsections, and means electrically insulating saidsections in all directions from eachother, from the earth, from saidfoundation structure and from said furnace walls.

walls, and floor slabs bridging said sections and electrically insulatedtherefrom.

5. A furnace house for furnace pots used in the electrolytic productionof aluminum, comprising side walls, and means for supporting a pluralityof furnace pots between said walls arranged end to end substantially ina row along one of said walls and comprising .a foundation structure, afloor supporting reinforced concrete structure supported on saidfoundation structure and constituting a plurality of sections, at leastsome of which are arranged along said wall and extend from the Vicinityof said wall inwardly towards the vicinity of said row of furnace pots,means for supporting the furnace pots on said sections, and meanselectrically insulating said sections in all directions from each other,from the earth, from said foundation structure and from said furnacewalls.

6. A furnace house for furnace pots having anodic parts and used in theelectrolytic production of aluminum, comprising side walls, and meansfor supporting a plurality of furnace pots in a row end to end betweensaid walls comprising a foundation structure, a floor supportingreinforced concrete structure supported on said foundation structure andconstituting a plurality of sections extending in spaced relationshipalong said row of pets on opposite sides of said row and extending intothe regions between the ends of said pots, means for supporting thefurnace'pots on said sections, means for supporting said anodic parts onsaid sections in the regions between the ends of said pots, and meanselectrically insulating said sections in all directions from each other,from the earth, from said foundation structure, from said furnace wallsand from said anodic parts.

7. A furnace house'for furnace pots used in the electrolytic productionof aluminum comprising side walls, and means for supporting between saidwalls a plurality of furnace pots arranged in substantially parallelrows and comprising a foundation structure, a floor supportingreinforced concrete structure supported on said'foundation structure andconstituting a plurality ofsections, some of which extend from some ofsaid furnace walls inwardly towards the adjacent rows of pots and othersof which .extend between the rows of pets, means for supporting thefurnace pots on said sections, and means electrically ported on saidfoundation structure and constituting a plurality of sections extendingin spaced relationship along said row of pots on opposite sides of saidrow and extending into the regions between the end of the pots, means ifor supporting the furnace pots on said sections, and

- means electrically insulating said sections in all directions saidfoundation structure comprises foundation pedestals extending into theground and said sections have supports seated on said pedestals butseparated therefrom by electrically insulating layers. V

4. A furnace house for furnace pots used in the electrolytic productionof aluminum, comprising side walls on .said sections, means electricallyinsulating said sec.-

tions in, all directions from each other, from the earth,

from said foundation structure and from said furnace insulated from saidsections.

from each other, from the earth, from said foundation structure and fromsaid furnace walls, and bridging concrete slabs extending between saidsections and electrically 9. A furnace house for furnace pots havinganodic parts and used in the electrolytic production of aluminum,comprising side walls, means for supporting between said walls aplurality of furnace pots arranged in a plurality of substantiallyparallel rows with the pots in each row extending end to end comprisinga foundation structure, a floor supporting reinforced concrete structuresupported on saidfoundation structure and constituting a plurality ofsections, some of which are spaced along the rows of pots and extendfrom some of said furnace walls inwardly towards the adjacent rows ofpots into the regions between of the pots in the latter roWs of pets,means for supporting the furnace pots on said sections, means forsupporting the anodic parts on said sections between the ends of thepots, and means electrically insulating said sections in all directionsfiom each other, from the earth, from said foundation structure, fromsaid furnace wall, from said anodic parts and from said pots, and floorslabs bridging said sections along the rows of pots and electricallyinsulated from said sections.

References Cited in the file of this patent UNITED STATES PATENTS HoodApr. 15, 1958 Syz et al. Feb. 17, 1959 Conway Apr. 18, 1961 Hegland July3, 1962

1. A FURNACE HOUSE FOR FURNACE POTS USED IN THE ELECTROLYTIC PRODUCTIONOF ALUMINUM, COMPRISING SIDE WALLS, AND MEANS FOR SUPPORTING A PLURALITYOF FURNACE POTS BETWEEN SAID WALLS COMPRISING A FOUNDATION STRUCTURE, AFLOOR SUPPORTING REINFORCED CONCRETE STRUCTURE SUPPORTED ON SAIDFOUNDATION STRUCTURE AND CONSTITUTING A PLURALITY OF SECTIONS EXTENDINGBETWEEN SAID WALLS AND SAID FURNACE POTS, MEANS FOR SUPPORTING THEFURNACE POTS ON SAID SECTIONS, AND MEAND ELECTRICALLY INSULATING SAIDSELECTIONS IN ALL DIRECTIONS FROM EACH OTHER, FROM THE EARTH, FROM SAIDFOUNDATION STRUCTURE AND FROM SAID FURNACE WALLS.